WO1998012240A1

WO1998012240A1 - Thermoplastic elastomers

Info

Publication number: WO1998012240A1
Application number: PCT/EP1997/004905
Authority: WO
Inventors: Konrad Knoll; Hermann Gausepohl; Norbert Niessner; Paul Naegele
Original assignee: Basf Aktiengesellschaft
Priority date: 1996-09-19
Filing date: 1997-09-09
Publication date: 1998-03-26
Also published as: EP0927210B1; TW403770B; EP0927210A1; DE59701918D1; DE19638254A1

Abstract

Thermoplastic elastomer moulding compounds based on a rubber elastic block copolymer are obtained by hydrogenating a styrene-butadiene block copolymer composed of at least one block A that forms a hard phase and contains polymerised styrene units and of at least one elastomer block (B/S) that forms a soft phase and contains polymerised styrene and butadiene units. The glass transition temperature Tg of block A of the styrene-butadiene block copolymer lies above 25 °C and that of its block (B/S) lies below 25 °C. The phase volume ratio between blocks A and B/S is selected so that the proportion of hard phase in the total block copolymer equals 1 to 40 vol % and the weight percentage of diene is lower than 50 wt %.

Description

Thermoplastic elastomers

description

Block copolymers of vinyl aromatic compounds (eg styrene) and dienes (eg butadiene) are copolymers of several polymer molecule regions (so-called blocks) which are strung together or linked in some other way and are more or less uniformly structured. You can 3e on the structure and content of diene monomer - at limited hours ^¬ th temperature - a total of either elasto ere, elastomeric or rigid, non-elastomeric own sheep have en it ie behave outwardly total of either similar to a polydiene are of importance, for example, as so-called SB rubbers (styrene-butadiene rubbers) or as transparent, impact-resistant styrene polymers. It is customary, based on the designations for impact-modified polystyrene, to designate those parts of the molecule which determine the rubber-elastic behavior as the calibration phase and the rigid parts of the molecule (the more or less pure polystyrene part) as the hard phase.

SB rubber, like ordinary diene polymers, has to be vulcanized for use, which severely limits their use and makes processing more expensive. A disadvantage is also the low aging and temperature resistance, which can be eliminated by hydrogenation, but also means an increase in price.

Hydrogenated styrene-butadiene-styrene and styrene-isoprene-styrene-πThree block copolymers with a diene content of approx. 70% are currently also commercially available (e.g. Kraton® G from Shell Inc. and Septon® from Kuraray). This is extremely thixotropic products, which have a high melt viscosity at low shear rates and can therefore only be processed with difficulty by injection molding, deep-drawing or calendering. The usual aid - white oil - also worsens the mechanical properties of the molded parts and leads to a high global migration rate which limits the use of the molded parts e.g. excludes in the food and toy sector.

The invention normally relates to transparent, purely thermoplastically processable hydrated styrene-butadiene block copolymers (styrene and butadiene also representing their technical equivalents) with elastomeric behavior and special mechanical and improved thermal properties, which are reduced by anionic polymerization. The ZJ so-called polymers (livmg polymers) carry out aniomically see polymerization, in which the growth of a chain molecule takes place at one end of the chain, due to the lack of spontaneous chain termination or transfer reaction theoretically living for as long as possible (remaining capable of polymerization) and the implementation of the living As is known, polymers rr c mono- or re t nonal reaction partners offer a versatile possibility for building up lock copolymers, although the choice of monomers is limited; In practice, only block copolymers of methyl aromatic compounds, that is to say styrene and its technical equivalents on the one hand and dienes, m essential butadiene or isoprene on the other have gained importance. Block copolymers are obtained by polymerizing until the monomer stock is exhausted and then changing the monomer. This process can be changed.

Linear EICCKCODOI mere werαer. e.g. B. m the US Pat. Nos. 3,507,934 and 4,122,134 cescnrieoer .. Stern: rmiσe block copolymers are currently. from U.S. Patents 4,086,298; < _* 167 15 and α 3 639 517 known.

The Eigenscnaf tsprof il this 3locκcopolymeren wirα substantially duren _enmonomere the copolymerized Z, Lange, arrangement and amounts ie ^{ra tio} of Pol αien- and determines polystyrene blocks. Zaruoerninaus spie .: the way of the transition between the lower right corner plays an important role: so-called senarfe unα tned (tapered) Uberσanqe, depending on, C _D the monomer change abruptly takes place all too slowly. In the event of a smeared transition, there is less or less statistical verification of Polydier and Polystyrene seauenn _^ annnemaic of a cest: r_τιten Ketter.seσmer.ts a _^ r

Blocκcopo_yτnere with mustardly separated blocks with identical molecular weight and lien fraction less tan than those with a sealed BlocKUDerσanα. ^' . ^" ιll man zα z heren ElocKcopolvmerer., you will prefer folilicn Ξlockuoergange with statistical sequence length distribution of 2ιen- and S yroiseα ducks in the TransitionDere :: r. (vσ_ US-PS 4 122 134 and EP-A-0 316 671) .

The scorched Ξ_ockuoergange your controlled

Changing the monomer supply is now expensive and causes a longer reaction time or less space-time consumption, which increases the manufacturing costs. I ⁷ - borderline case, the continuously controlled I-gaoe (cf. US Pat. Nos. 4,346,198 and 4,248,984), the implementation: extremely long because of the unfavorable position of the coporization parameters of Vmylaromatics and dienes extremely .r.α one αewir.rt nαr polymers mt i nc oσener distribution of butadiene and vinyl aromatic Emheiten in the area of the Bloc - _T RANSITIONAL, which affects how an increase in the number of transitions. This is clearly shown by a low glass transition temperature (T _g below -50 ° C, see US Pat. No. 4,346,198, Example 1) and poor processing properties.

The morphological examination of block copolymers shows that when the block transition is smeared, the sequence length of the pure diene phase is shifted relative to the polystyrene phase and thus the volume ratio is shifted in favor of the diene phase.

The invention has set itself the task of creating a suitable molecular structure to aging and weather resistant elastomeric, that is to say rubber-block copolymers of Vmylaromatics and dienes, especially styrene, which are technically easy to manufacture, as tough as possible and are easy to process without the use of tools such as thermoplastics on extruders and injection molding machines.

According to the invention, this is, in general terms, possible by hydrogenating a styrene-coputadiene block copolymer which has been thawed out from blocks which harden a hard phase (Elock type S) from styrene-E and those which have a soft phase (block type (B / S )) from butadiene and styrci units with a static distribution of the butadiene and styrene units. The structure along the chain m statistical means can be homogeneous or inhomogeneous. As already noted, styrene and eutadiene are also available. for their respective technical equivalents (alkyi, especially methyl-styroie and Dipher.yϊetr.yier. or Isopre and Dimetr.ylcutadiεn).

Immediate subject matter of the invention is a rubber-elastic block copolymer, which has been obtained by hydrogenation of a styrene-butadiene-elock copolymer, which consists of at least two hard phase-forming elastomers S having polymerized units of the styrene and at least one polymerized units of both the styrene and the Butadiene-containing elastomeric, a soft-phase-forming block (B / S) exists with the measure that the chain ends of an Eloc copolymer are essentially each formed by a block S, the glass temperature T _{g of} the Elockε S above 25 ° C. and that of the less hydrated. Blocks (B / S) is below 25 ° C and the phase volume ratio of the blocks S to the blocks E / S has been selected so that the proportion of hard pnaεe (blocks S) in the total Elockcopolymensat 1 to 40 Volume% and the weight fraction of the diene is less than 50 wt .-%.

A weather-resistant and aging-resistant, highly flowable, rubber-elastic block copolymer is obtained in that the soft phase (B / S) is formed from a statistical copolymer of styrene (the vinyl aromatic compound) with butadiene (the diene) within the scope of the above parameters ; Statistical copolymers of Vmylaromaten and dienes are obtained by polymerization either according to a proposal of the German patent application P 44 20 952.5 by adding polar, coordinating solvents or in the presence of a potassium salt soluble in non-polar solvents. Statistical copolymation of styrene and butadiene succeeds e.g. according to S.D. Smith et al., A. Ashraf et al. (Polymer Preprmts 34 (2), 672 (1993) and 35 (2), 466 (1994) in that potassium 2, 3-dimethyl-3-pentanolate or potassium 3-ethyl-3-pentanolate are used as the potassium salt .

The difference between the two methods is that the

The ratio of the 1,2- to 1,4-linkages of the diene in the presence of an appropriate concentration of the potassium salt (lithium-potassium ratio greater than 25: 1) in a non-polar solvent remains below 11%, based on the sum of 1 , 2-Vmyl and 1,4-cιs- and trans-microstructure, while in the presence of a polar cosolvent this proportion is higher. In the case of polymerization initiated with butyllithium in cyclohexane, the molar ratio of lithium to potassium should be about 10 to 1 to 40 to 1, with a particularly small proportion of 1, 2 compounds being about 25 to 1 to 40 to 1. If a composition gradient is to be achieved along the butadiene / styrene block with an otherwise statistical distribution of butadiene and styrene, a Li / K ratio above about 40 to 1 should be selected if the gradient is to change from butadiene to styrene; in the case of a gradient from styrene to butadiene, conversely, a Li / K ratio below 10 to 1 should be chosen.

A starting material suitable for the hydrogenation according to the invention (styrene-butadiene block copolymer) can e.g. can be represented by one of the following general formulas 1 to 11:

(1) (S- (B / S)) _{n +} ι;

(2) (S- (B / S)) nS; (3) (B / S) - (S- (B / S)) _n ;

(4) X - [(S- (B / S)) _n ] _{m +} ι;

(5) X - [((B / S) -S) _n ] _{m + 1} ; (6) X - [(S- (B / S)) _r. -S] _m -. ₁ ;

(7) Xt ((B / S) -S) _R - <B / S)] _{m + i}

(8) Y - [(S- (B / S)) _{r m +} ι;

(9) Y- [((E / S) -S) _n ] _m , _i; (10) Y - [(S- (B / S)) r-S] _{m +} ι;

(11) Y - [((E / S) -S) _n - (B / S)] _{m + i} ;

where S stands for the vinylaromatic (styrene) BIOCK and (B / S) for the soft phase, i.e. the Elock statistically composed of butadiene and styrene units, X the rest of an n-functional initiator, Y the rest of an ir .-functional coupling no. t els and m and r. natural numbers from 1 to 10 mean.

An Elockcopolymensat of one of the general formulas is preferred

S- (B / S) -S (according to formula (2) with r. = 1); X - [(B / S) -S ^ ₂ (corresponding to the formula (Ξ) with r = n - 1); and Y- [(B / S) -S ^" . (according to formula (9) with r = n = 1).

A block polymensate is preferred, the soft side (3 / S) of which is divided into m blocks

(12) (B / S) _ä - (B / S) _b ; (13) (B / S) _a - (B / S) _D _ (B / S) _a ; (14) (B / S) _6. (E / S) _D - (B / S) _C ;

where, a, b, c ... each means differently composed Blccκe De - indicates, ie their styrcl / butadiene ratio may be different or change within an EIOCKS, in particular z ner. men, ie for three different parts iock (B / S) _, (3 / S ι _z and (B / S) - the following applies, for example: (S: B) <(S: B) _r <(S: E ) _C.

Particularly preferred is a Styrcl-butadiene Ξiockcopolymerisat whose soft phase in two or more identical blocks (B / _S): - (B / S) _A: (E / S) is divided ... _a3.

A blocopolymer that has several blocks ((/ S) and / or S with different molecular weights per molecule is also preferred.

The above-described lock copolymers are hydrogenated according to the invention, ie the chemical double bonds resulting from the incorporation of the diene are removed, so that essentially an ethene-butene-styrene copolymer is formed, the ethene-butene ratio being easily visible through the behavior According to the linked 1,2- to 1,4-M κrcs structure. De- is true. Polymers with a high ethene-butene ratio, such as those formed by polymerization in the presence of potassium salts, have a crystalline content, assigned to the polymer segments which correspond to a polyethylene. These polymers are stiffer than those obtainable by means of polar cosolvents with the same block structure but a lower ethene-butene ratio.

For experimental purposes, an in situ catalyst can be used at a hydrogen pressure of e.g. Hydrogen 5 to 50, preferably 10 to 20 bar at about 100 to 200 ° C. Typically, nickel octanoate or nickel acetyl acetonate toluene are reduced with aluminum alkyl to colloidal nickel. The nickel suspension is added to the dissolved polymer, which may or may not be deactivated. Depending on the temperature, the implementation takes 10 to 20 hours entitlement; you can see the progression e.g. Track odometrically on a sample and later use the values found for technical operation.

To e.g. In order to obtain a product that can be used in the food sector, hydrogenation on a carrier-bound catalyst, particularly preferably continuously on a catalyst arranged firmly in a tower, is recommended.

The aged thermoplastic elastomers according to the invention are extremely suitable for the production of rubber-elastic molded parts with the usual methods of thermoplastic processing, e.g. to foils, foam, thermoforming, molding molds or extruded profiles.

Preferred as a y yromatic compound in the sense of the invention is styrene and also α-methylstyrene and V yltoluoi and mixtures of these compounds. Preferred dienes are butadiene and isoprene, also piperylene, 1-phenylbutadiene and mixtures of these compounds.

A particularly preferred monomer combination is butadiene and styrene. All of the weight and volume data used in this description, and in particular the following, relate to the combination of butadiene and styrene; When using the technical equivalents of styrene and butadiene ("styrene monomer" and "diene monomer"), the information must be converted accordingly. The (B / S) block is built up from 75 to 30% by weight yroltyrene monomer and 25 to 70% by weight diene monomer. A soft block particularly preferably has a diene content between 35 and 70% and a styrene content between 65 and 30%.

The weight fraction of the diene in the entire block copolymer is 15 to 65% by weight in the case of the monomer combination styrene / butadiene, and that of the yroltyrene monomer is correspondingly 85 to 35% by weight. Butadiene-styrene block copolymers with a monomer composition of 25 to 60% by weight of butadiene and 75 to 40% by weight of styrene monomers are particularly preferred.

The block polymers are prepared by anionic polymerization in a non-polar solvent, the initiation being carried out using organometallic compounds. Compounds of alkali metals, especially lithium, are preferred. Examples of initiators are methyl lithium, ethyl lithium, propyllithium, n-butyllithium, se-butyllithium and tert-butyllithium. The organometallic compound is added as a solution to a chemically different (inert) hydrocarbon. The dosage depends on the desired molecular weight of the polymer, but is generally in the range from 0.002 to 5 mol%, if it is based on the monomers. (Cyclo) aliphatic hydrocarbons such as cyclonexane or methylcyclohexane are preferably used as solvents.

According to the invention, the statistical blocks of the block copolymers which simultaneously contain styrene monomer and butadiene are prepared with the addition of a potassium acid, in particular a potassium alkolate, which is detached from the reaction mixture. It genuσt εenon a small Menae Kaliu ion, generally from 2 to 10 mol%, based on the amount of lithium to which he dungsgemaßen statistical see installation v _^ r. , to effect tyrcl and butadiene.

Above all, the potassium salts of tertiary alcohols have at least 7 carbon atoms. Typical alcohols are e.g. 3-ethyl-3-pentanol and 2, 3-dimethyl-3-pentanol. Tetrahydrol alool (= 3, 7-dimethyl-3-octanol) proved to be particularly suitable. In addition to potassium alcoholates, other potassium salts are also suitable which have a low behavior towards metal alkyls. Potassium salts of dialkylamides, alkylated diarylamides, alkylthiolates and alkylated arylthioates should be mentioned.

The point in time at which the potassium salt is added to the reaction medium is important. Usually at least parts of the

Solvent and the monomer for the first Elock presented in the reaction vessel. To avoid the potassium salt from traces of protic impurities is at least partially hydrolyzed to KOH and alcohol, the lithium organyl should first be added and mixed in, only then the potassium salt. If the first block is a homopolymensate, it is advisable to add the potassium salt shortly before the statistical block is polymerized, ie after changing the monomer mixture.

The potassium alcoholate can be easily removed from the corresponding alcohol by stirring a solution of the alcohol cyclohexane in the presence of excess potassium-sodium alloy or, in a

Temperature above the melting point of potassium (i.e. 64 ° C), presence of pure potassium. At 25 ° C, the evolution of hydrogen and thus the reaction is complete after 24 hours. The reaction can be shortened to a few hours at 80 ° C (reflux). Alternatively, it is advisable to add a small excess of an alcoholate such as potassium methyl, potassium ethylate or potassium tert-butoxide in the presence of a high-boiling solvent such as decalin or ethylbenzene, to distill off the low-boiling alcohol and to take up the residue with cyclohexane. The excess donor alcoholate can then be filtered off.

The ratio of the 1,2-linkages to the sum of 1,2- and 1,4-linkages of the diene, as is the case with anionic

Polymerization of pure butadiene is increased by a maximum of 1 to 2% by means of potassium alcoholate (with a Li / K ratio above 30) and is then, based on experience, between about 9 and 11%.

The polymerization temperature can be between about 0 and 130 ° C. The temperature range between 30 and 100 ° C. is preferred.

The volume fraction of the soft phase in the solid is of decisive importance for the mechanical properties of the styrene-butadiene / styrene block copolymers according to the invention. Erf dungsgemaß the volume fraction of built up from butadiene, and vinylaromatic sequences soft phase is 60 to 95, preferably from 70 to 90 and particularly preferably at 80 to 90 vol ⁹ o. The formed from the vinyl aromatic monomers

Blocks S form the hard phase, the proportion by volume of which corresponds to 5 to 40, preferably 10 to 30 and particularly preferably 10 to 20 V%.

It should be noted that between the above

Ratios of vmylaromatic compound and diene, the limit values of the phase volumes and the Composition, which results from the ranges of the glass temperature according to the invention, there is no strict correspondence since they are numerical values rounded to the nearest ten digits. Rather, this could only happen by accident. 5

The volume fraction of the two phases can be measured by means of contrasted electron microscopy or solid-state NMR spectroscopy. The proportion of vinyl aromatic blocks can be determined by osmium breakdown of the polydiene fraction by falling and weighing. The

10 future phase ratio of a polymer is also let out of the amounts of monomers used to calculate when each completely let polymerize n ^¬ dig. It can be assumed that the density of the monomer units for styrene monomers and diene monomers is identical.

15

In the sense of the invention, the block copolymer is clearly defined by the quotient of the volume fraction m percent of the soft phase formed from the (B / S) blocks and the proportion of diene units m of the soft phase, which is used for the combination styrene /

20 butadiene is between 25 and 70% by weight

Due to the statistical incorporation of the vinyl aromatic compounds, the soft block of the block copolymer and the use of potassium alcoholate during the polymerization

25 affects the glass transition temperature (T _g ). It is typically between -50 and + 25 ° C, preferably -50 to + 5 ° C. Since 1,2-poly butadiene has a glass transition temperature which is 70 to 90 ° C higher than 1, 4-polybutadiene, the glass-based statistical copolymers, which are exposed to potassium, are responsible for the

30 uoergangs e perature on average by 2 to 5 ° C lower than in the corresponding Lewis base products, which have a higher proportion of 1, 2-butadiene linkages.

The molecular weight of block S is l.a. between 1000 and 35 200,000, preferably between 3,000 and 80,000 [g / mol]. S blocks can have different molecular weights within a molecule.

The molecular weight of the block (B / S) is usually between 2,000 and 250,000 [g / mol], values between 40,000 and 150,000 [g / mol] are preferred.

Like Block S, an EIOC (B / S) can also have different molecular weight values within a copolymer molecule.

45 The coupling center X is formed by the reaction of the living anionic chain ends with an at least bifunctional coupling agent. Examples of such combinations are shown in U.S. Patents 3,985,830, 3,280,084, 3,637,554, and 4,091,053. For example, epoxidized glycerides such as epoxidized linseed oil or soybean oil are preferably used; Divmyl benzene is also suitable. Dichlorodialkylsilanes, dialdehydes such as terephthalaldehyde and esters such as ethyl formate, ethyl acetate or ethyl benzoate are particularly suitable for the dimensioning.

Preferred polymer structures are S- (B / S) -S, X - [(B / S) -S] ₂ and

Y- [(B / S) -S] ₂ where the statistical block (B / S) itself is again divided into blocks (Bi / Aj.) - (B ₂ S ₂ ) - (B3 / S3) - ... can. The statistical block preferably consists of 2 to 15, particularly preferably 3 to 10, partial blocks. The division of the statistical block (B / S) into as many partial blocks as possible offers the decisive advantage that even with a gradient of the composition within a partial block, which is difficult to avoid under polymeric conditions under practical conditions (see below) the (B / S) block as a whole behaves like an almost perfect statistical polymer. It is therefore advisable to add less than the theoretical amount of potassium alcoholate. A larger or a smaller proportion of the sub-blocks can be equipped with a high proportion of diene. This means that the polymer maintains a residual toughness even below the glass transition temperature of the OC-predominant (B / S) block and does not become completely brittle.

The block copolymers according to the invention have a spectrum of properties which is very similar to that of plasticized PVC, but can be produced completely free of migration-capable, low molecular weight plasticizers. They are stable against crosslinking under the usual processing conditions (180 to 220 ° C). The high stability of the polymisates according to the invention against crosslinking can be clearly demonstrated by rheography of the melt. The arrangement of the tests corresponds to that of an MVR measurement. If the flow rate is constant, the pressure increase as a function of time is recorded. The polymers according to the invention show even after 20 min. no pressure increase at 250 ° C and result in a smooth melt strand.

The block copolymers according to the invention are furthermore distinguished by a high oxygen permeation P ₀ and water vapor permeation P, of over 2,000 [cm ³ 100 mm / m ² d bar] and over 10 [g 100 mm / m ² d bar], where P ₀ indicates the amount of oxygen cm ³ or P ^ the amount of hydrogen in grams, which pass through 1 m ^{2 of} film with a standard thickness of 100 mm e day (d) and bar pressure difference per bar. A high restoring force for deformation, as observed with thermoplastic elastomers, high transparency (over 90% with a layer thickness of 10 mm), a low welding temperature of less than 120 ° C and a wide welding range (over 5 ° C) with a moderate one Stickiness makes the block copolymers according to the invention a suitable starting material for the production of so-called stretch or stretch films, infusion tubes and other extruded, injection-molded, thermoformed or blow-molded finished parts for which high transparency and toughness are required, especially for applications in the field of medical technology.

The polymerization is carried out in several stages and, for mono-functional initiation, e.g. started manufacturing the hard block S. Some of the monomers are placed in the reactor and the polymerization is started by adding the initiator. In order to achieve a defined chain structure that can be calculated from the monomer and initiator metering, it is advisable to run the process up to a high conversion (over 99%) before the second monomer is added. However, this is not absolutely necessary.

The sequence of the monomer addition depends on the selected block structure. With monofunctional initiation e.g. first the vmylaromatiscne compound either submitted or metered directly. A cyclohexane solution of the potassium alcoholate is then added. After that, butadiene and styrene should be added at the same time if possible. The statistical structure and composition of the BIOCKS (B / S) are determined by means of the ratio of butadiene to methyl aromatic compound, the concentration of the potassium salt and the temperature. According to the invention, the butadiene takes up a proportion by weight of 25% to 70% e relative to the total mass, including methyl aromatic compound. Block S can then be polymerized by adding the vinyl aromatic. In addition, the polymer blocks can also be connected to one another by the coupling reaction. In the case of bifunctional initiation, the (B / S) block is built up first, followed by the S block.

Further processing takes place according to the usual procedures. It is advisable to work in a Ruhr kettle and to protonate the carbanions with an alcohol such as isopropanol, to make the polymer weakly acidic with CO ₂ / water before further processing, the polymer with an oxidation inhibitor and a radical scavenger (commercial products such as Trisnonylphenyl - pnosphite (TNPP) or α-tocopherol (vitamin E) or under the trade name Irganox® 1076 or Irganox 3052 from Cba-Geigy, Basel obtainable products) to stabilize, remove the solvent by the usual methods, extrude and granulate. Like other types of rubber, the granulate can be protected against sticking with a commercially available antiblocking agent such as Acrawax®, Besquare® or Aerosil®.

The hydrogenation of the block copolymers can be carried out according to the rules which are generally known for reactions on polymers on the one hand and for the hydrogenation of olefinic double bonds on the other hand.

For experimental purposes, a solution of the hydrogenation catalyst is conveniently prepared as follows: A 20% solution of aluminum triisobutyl in hexane is added to a 1% solution of nickel acetylacetonate in toluene at room temperature, where the weight ratio of nickel acetyl acetonate to truεobutyl alum ium ium ium range : 4 lies. After the exothermic reaction has subsided, the fine catalyst solution is added to the polymer solution and hydrogen is added. 1.5 kg (0.15% by weight) of nickel acetylacetonate are sufficient per kg of polymer; if the reaction mixture is particularly pure, 0.15 g is sufficient. The achievable hydrogenation rate depends on the catalyst concentration, hydrogen pressure and reaction temperature. Desired hydrogenation levels of over 95% can be achieved after 30 to 120 minutes at 15 bar hydrogen partial pressure and temperatures between 180 and 200 ° C. At temperatures around 120 ° C, the hydrogenation takes 8 to 16 hours. A good mixing of the hydrogen gas is a prerequisite for a good space-time yield. For this, an effective stirrer with good vigorous mixing is required, which also creates a surface, since gas can be used as a solution. So-called agitation stirrers are very suitable. After the hydrogenation has ended, the colloidally distributed nickel, which colors the polymer solution black, can be oxidized with a decolorization using a hydrogen peroxide / acetic acid mixture.

The hydrogenation can of course also be carried out with other homogeneous and heterogeneous hydrogenation catalysts, particularly on an industrial scale. Hydrogenation on a fixed bed catalyst is particularly interesting because the polymer is prevented from becoming contaminated by catalyst residues.

It is recommended that hibitor the hydrogenated polymer with a Oxidationsm and a radical scavenger (commercially available products such as trisnonylphenylphosphite (TNPP) or α-Tocopherol (vitamin E), for example under the trade name Irganox ^® 1076 or Irganox 3052 available products) and optionally a UV-Stabilisatcr to εtabili Use the public method to remove, extrude and granulate the solvent. Like other types of rubber, the granulate can be protected against sticking with an antiblocking agent, for example a commercial product such as Acrawax ^® , Besquare® or Aerosil ^® . All in all, much smaller amounts of additive are sufficient compared to the unhydrogenated products, since the chemical stability increases due to the hydrogenation and the tendency to stick decreases.

Examples

A) Preparation of the block copolymers

The required block copolymers were each in a simultaneously heatable and coolable 50 1 stainless steel autoclave, equipped with a crossbar stirrer and by rinsing with nitrogen, boiling with a solution of sec-butyllithium and 1,1-diphenyl ethylene (mol ratio 1: 1) prepared in cyclohexane and drying.

To this end, 22.8 liters of cyclohexane were introduced and the amounts of initiator, tetrahydrofuran and monomers given in Table 1 were added. The polymerization time, start and end temperature are also given, the monomer feed time always being short compared to the polymerization time.

The temperature of the reaction mixture was controlled as required by heating or cooling the reactor jacket. After conversion ene (consumption of the monomers), the appropriate coupling agent was reacted (titrated) up to the FarDlosιgκeιt and acidified with a 1.5-fold excess of formic acid, the solutions obtained were immediately, without the addition of stabilizers or other processing - steps used.

B) hydrogenation

50 ml of a 20% solution of aluminum triisobutyl n hexane are added to 250 ml of a 1.136% by weight solution of nickel acetylacetonate in toluene at room temperature, so that the weight ratio of nickel acetylacetonate to triisobutyl aluminum is in the range of 1: 4. After the weak exothermic reaction has subsided, the fresh catalyst solution is added to 13.3 kg of a 15% polymer solution and 15 bar of hydrogen are added. With stirring, the boiler content is heated to 120 ° C. A degree of hydrogenation of 95% is reached after 8 hours and 98% after 16 hours. The degree of hydrogenation is determined by Wij s titration Sample of the hydrogenated in relation to the unhydrogenated solution determined. After the hydrogenation has ended, a mixture of 12 ml of hydrogen peroxide, 2.5 ml of formic acid and 50 ml of water is added to the black solution at 70 ° C. The kettle content becomes colorless immediately after addition. The solution is freed from the solvent on a degassing extruder and granulated.

For the mechanical measurements, 2 mm thick plates were pressed (200 ° C, 3 mm) and standard test pieces punched out.

Table 1:

Polymerization and analysis of linear S-SB-S block copolymers or

(Examples 3 and 6) Star block copolymer [S- (S / B)] X

Continuation of table 1:

0

a) ethyl formate; b) Edenol B 316 (Henkel) _5 c) there are 2 glass transition stages each running over the specified range, which can presumably be assigned to the chemically different polymer districts.

Table 2: 0 mechanical properties (all values m [N / mm ² ])

5

0

5

0

5

Claims

claims

1. Thermoplastic elastomeric molding composition based on a rubber-elastic block copolymer, the hydrogenation of a styrene-butadiene block copolymer from at least one polymerized units of the styrene having a hard phase forming block A and at least one polymerized units of both the styrene and the butadiene having elastomers , a soft phase-forming block (B / S) has been obtained, the glass transition temperature T _g of block A of the styrene-butadiene block copolymer above 25 ° C. and that of its block (B / S) below 25 ° C. and the phase Volume ratio of block A to block B / S had been chosen so that the proportion of the hard phase in the entire block copolymeπsat 1 to 40% by volume and the weight fraction of the diene was less than 50% by weight.

2. Molding composition according to claim 1, obtained by hydrogenation of a styrene-butadiene block copolymer, the block A of which

Glass temperature T _g above 50 ° C and its block (B / S) has a glass temperature T _g below 5 ° C.

3. Molding composition according to claim 1, characterized in that α-methylstyrene, vmyltoluene or diphenylethylene have been used instead of styrene and / or isoprene instead of butadiene.

4. Molding composition according to claim 1, characterized in that as a further soft phase em non-hydrated rubber-elastic

Styrene-butadiene copolymer is present in a minor amount.

5. Molding composition according to claim 4, characterized in that as the soft phase e copolymeπεat with statistical distribution of the comonomers has been hydrogenated in at least one block.

6. Molding composition according to claim 1, characterized in that em block polymer has been hydrogenated, as is obtained by anionic polymerization, if at least the polymerization of the soft block (B / S) has been carried out in the presence of a polar cosolvent.

7. Molding composition according to claim 1, characterized in that em block copolymer with several blocks (B / S) with different molar mass e molecule has been hydrogenated.

8. Molding composition according to claim 1, characterized in that a block copolymer with several blocks A with different ^¬ Licher molecular weight per molecule has been hydrogenated.

9. Molding composition according to claim 1, obtained by hydrogenation of a

Block copolymers represented by one or more of the general formulas (1) to (11)

(1) (A- (B / S)

(2) (A- (B / S)) n-A;

! 3) (B / S) - (A- (B / S)

(4) X- (A- (B / S) ⁾ _n ] m + ι;

(5) X- ((B / S) -S) _n ] _{m +} ι;

(6) X- (S-IB / S)) _n -S] _{m +} ι;

(7) X- ((B / S) -S) _n - (B / S)] _{m +} ι;

(8) Y-; s- (B / S)) _n ] _{m +} ι;

(9) Y- ((B / S) -S) _n ],

(10) Y-! S- (B / S)) _n -S] _{m +} ι;

11) Y- (B / S) -S) _n - (B / S)] _{m +} ι;

where S stands for styrene and B / S stands for the block constructed statistically from butadiene and styrene, X is the rest of an n-functional initiator, Y is the rest of an m-functional coupling agent and m and n are natural numbers from 1 to 10.

10. Molding composition according to claim 1, obtained by hydrogenation of a block copolymer with a block corresponding to the general formulas S — B / S-S, X - [(E / S) -S] ₂ and / or Y- [B / SS] ₂ .

11. Molding composition according to claim 1, obtained by hydrogenation of a block copolymer with one in blocks

(12) {B / S) _a - (B / S) _b ; (13) ⁽ B / S ⁾ a- ⁽ B / S ⁾ _b - ⁽ B / S ⁾ _a ; (14) (B / S) _a - (B / S) _b _ (E / S) _c ; divided soft phase, wherein a, b, c ... is in each case different composite blocks, whose styrene / butadiene comparison haltnis be different or to another within a block can in particular increase, wherein for three different part blocks (B / S) _a , (B / S) _b and (B / S) _c : (S: B) _a <(S: B) _D <(S: B) _c .